Sirex species (Hymenoptera: Siricidae) and their parasitoids in Pinus sylvestris in eastern North America

Siricids and their parasitoids were reared from Scots pine (Pinus sylvestris L. (Pinaceae)) trees infested by Sirex noctilio F. in central New York State. Sirex noctilio accounted for 94.3% of the siricid specimens, emerging, totaling 13 13 specimens from six frees, with a maximum of 495 from one tree. Of the individuals emerging per tree, 20.6 +/- 5.2% were female. Two native siricids, Sirex nigricornis F. and S. edwardsii Brulle, also emerged from trees but in low numbers. Three hymenopteran parasitoid species that attack siricicis emerged, totaling 21.8 +/- 6.4% parasitism per tree. Ibalia leucospoides ensiger Norton (Ibahidae) was by far the most abundant parasitoid, at 20.5 +/- 6.3% parasitism per free. The percentage of female S.noctilio emerging was positively correlated with wood diameter, whereas percent parasitism by I. I. ensiger was negatively correlated with wood diameter.